Low-frequency radar

From Wikipedia, the free encyclopedia

Low Frequency Radar is the use of radars which use frequencies lower than 1 GHz, as opposed to the usual Radar bands which can range from the X band at 8-12 GHZ to the Ka band which tops out at 40 GHz.

The radar cross section of any target depends on the radar transmitted frequency. Below 900 MHz the target radar cross section increases exponentially, however the increased radar cross section means that there is much more radar return from undesirable sources, such as cloud cover and rain (cf. weather radar). It is because of this that radars are traditionally at much higher frequency, with an exception being the radars operated in the 3-30 MHz band which are used as over-the-horizon radar stations because signals in that range are able to reflect off of the ionosphere.

Recently, there has been interest in developing radars which operate in these low frequencies to help counter the advancement in stealth technology, by applying advanced digital signal processing to these bands in order to remove much of the 'clutter', but there are still problems with this. Low-frequency radar installations are generally quite large and thus makes them difficult to transport, as well as making them an easy target.